The Deccan Trap Formation was caused by

The Deccan Trap formation is a classic example of a Large Igneous Province (LIP) characterized by flood basalt eruptions [4]. During the Late Cretaceous period, approximately 66 million years ago, enormous quantities of highly fluid basaltic lava were poured out through fissures and cracks in the Earth's crust [3]. This low-viscosity lava flowed over vast distances, covering about 5 lakh sq km of the Indian subcontinent with thick, multiple layers of tholeiitic basalt [6]. These eruptions were of the Hawaiian or fissure type, where explosive activity was largely absent, allowing the lava to spread and form a massive plateau rather than a steep volcanic cone [5]. The resulting stratigraphic sequence reaches thicknesses of over 2,000 to 3,000 meters in regions like the Western Ghats [5]. While some sources describe the overall feature as a massive shield volcano due to its scale, the primary mechanism is defined as flood basalt volcanism [4].

Sources

1. [4] FUNDAMENTALS OF PHYSICAL GEOGRAPHY, Geography Class XI (NCERT 2025 ed.) > Chapter 3: Interior of the Earth > Flood Basalt Provinces > p. 24
2. [2] Geography of India ,Majid Husain, (McGrawHill 9th ed.) > Chapter 2: Physiography > 6. The Deccan Trap > p. 51
3. [3] Physical Geography by PMF IAS, Manjunath Thamminidi, PMF IAS (1st ed.) > Chapter 11: Volcanism > Fissure Type or Flood Basalt Volcanoe (Lava Plateaus) > p. 141
4. [1] Geography of India ,Majid Husain, (McGrawHill 9th ed.) > Chapter 1: Geological Structure and formation of India > THE CRETACEOUS SYSTEM (THE DECCAN TRAP) > p. 19
5. [5] https://www.sciencedirect.com/topics/earth-and-planetary-sciences/deccan-traps
6. [6] https://en.wikipedia.org/wiki/Deccan_Traps